Self dunnaged cathode bundle

ABSTRACT

A method for producing self-dunnaged cathode bundles, comprising the steps of forming at least one deformed cathode by bending opposed ends of at least one cathode to form a pair of supports disposed at an angle to a central portion of the at least one deformed cathode, and stacking one or more further cathodes above or below the at least one deformed cathode.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application PCT/AU2008/000226, filed on Feb. 20, 2008, which application is hereby incorporated by reference in its entirety.

BACKGROUND

Electrorefining and electrowinning, also known as electroextraction, are processes by which valuable metal ions may be recovered from solution by electrolytic deposition of metal onto a solid substrate acting as an electrode. Electrorefining is commonly used as an extraction process for a large number of metals, including lead, copper, gold, silver, zinc, aluminum, cobalt, chromium and manganese.

The metal deposited onto the electrode forms sheets known as cathodes. These cathode sheets are removed from the electrode and a number of cathodes are stacked flat to form a cathode bundle, weighing several tonnes, ready for transportation for sale or to a further refining process. Typically, a cathode bundle is strapped to hold the bundle together. When cathode bundles are stacked, pieces of wood, known as dunnage, are inserted between the cathode bundles. This dunnage acts to create a gap between cathode bundles of sufficient size to allow a forklift, or similar vehicle, to pick up and move the cathode bundle. Cathode bundles are also placed on temporary or permanent dunnage located on the ground to enable forklifts to pick up the cathode bundles.

The use of wood as dunnage presents a number of disadvantages, not least of which is the cost. The cost of the wood alone may amount to hundreds of thousands of dollars per year. In addition, wooden dunnage may leave marks on the cathodes it comes into contact with, which is not only unsightly, but can contaminate the surface of the cathode. In some circumstances, the use of wooden dunnage may also raise quarantine problems when cathode bundles are to be transported internationally.

SUMMARY

It is an object of the invention to provide a self-dunnaged cathode bundle which may overcome at least some of the abovementioned disadvantages, or provide a useful or commercial choice.

In one form, the present invention resides in a method for producing self-dunnaged cathode bundles, comprising the steps of forming at least one deformed cathode by bending opposed ends of at least one cathode to form a pair of supports disposed at an angle to a central portion of the at least one deformed cathode, and stacking one or more further cathodes above or below the at least one deformed cathode.

The self-dunnaged cathode bundles may be arranged in a number of different ways. In one embodiment of the invention, the at least one deformed cathode may be placed at the bottom of the cathode bundle and have one or more cathodes positioned above the at least one deformed cathode. In another embodiment, the at least one deformed cathode may be placed at the top of the cathode bundle and have one or more cathodes positioned below the at least one deformed cathode.

Alternatively, the self-dunnaged cathode bundle may comprise one cathode positioned below the at least one deformed cathode and a plurality of cathodes positioned above the at least one deformed cathode.

In some embodiments, the at least one deformed cathode may be placed on one or more other cathodes to form a cathode bundle having one or more cathodes positioned below the at least one deformed cathode and one or more cathodes above the at least one deformed cathode.

In use, the pair of supports of the at least one deformed cathode are long enough to provide a gap between the cathodes of sufficient size to allow the tines of a forklift, or similar device, to pass through and lift the cathode bundle. Self-dunnaged cathode bundles also eliminate the need to use wood as dunnage, substantially reducing operational costs and preserving the surface finish of the cathodes. In addition, by eliminating the use of wood, self-dunnaged cathode bundles reduce the waste generated by the process.

The supports of the at least one deformed cathode may be bent to any angle that will allow the supports to support the weight of the second plurality of cathodes placed on top of it. Typically, however, the at least one deformed cathode will be bent so that the supports make an angle of from 85-95°, more preferably from 87-93°, and most preferably from 89-91° to the central portion of the at least one deformed cathode. While not narrowly critical, it is preferred that, in use, the supports of the at least one deformed cathode extend downwardly from the central portion of the at least one deformed cathode. However, this invention is not limited to the supports extending downwardly from the central portion of the at least one deformed cathode, and in some aspects the supports may extend upwardly from the central portion of the at least one deformed cathode.

The process of bending the cathodes may be achieved by a number of known methods. However, it is preferred that the bending is performed mechanically during handling of the cathodes.

The thickness of a cathode sheet generally tapers towards the outer edges, a phenomena known as feathering. Thus, the placement of the bend in the cathode sheet to form the supports of the deformed cathode must be at a sufficient distance from the outer edge of the cathode sheet to avoid bending the thinnest portion of the cathode. While any distance that avoids the thinnest portion of the cathode would be suitable, it is preferred that the bend is placed from 50-300 mm, more preferably from 75-150 mm, most preferably approximately 100 mm from the outer edge of the cathode.

In an alternative embodiment of the invention, the at least one deformed cathode may be located at the bottom of the cathode bundle, with a plurality of cathodes stacked above the at least one deformed cathode.

The number of deformed cathodes may vary depending on the number of cathodes stacked above and the weight of those cathodes as well as the thickness (and hence strength) of the deformed cathode(s). However, typically a pair of cathodes will be bent. This pair of cathodes may be bent separately or together.

The self-dunnaged cathode bundle is particularly suitable for use with copper, nickel and zinc cathodes, although cathodes made from any metal could equally be stacked together using the present method. Similarly, flat or corrugated cathode sheets may be stacked using the method of the invention.

In another form of the invention there is provided a self-dunnaged cathode bundle comprising at least one dunnage cathode having a pair of supports disposed at an angle to a central portion, and one or more cathodes stacked above or below the at least one dunnage cathode.

Preferably the dunnage cathode is formed by bending.

In a preferred embodiment of the invention the at least one dunnage cathode is positioned at the bottom of the self-dunnaged cathode bundle and have one or more cathodes positioned above the at least one dunnage cathode. In another embodiment, the at least one dunnage cathode may be placed at the top of the cathode bundle and have one or more cathodes positioned below the at least one dunnage cathode.

Alternatively, the self-dunnaged cathode bundle may comprise one or more cathodes positioned below the at least one dunnage cathode and a plurality of cathodes positioned above the at least one dunnage cathode.

The number of dunnage cathodes may vary depending on the number of cathodes stacked above and the weight of those cathodes as well as the thickness (and hence strength) of the dunnage cathode(s). However, typically the at least one dunnage cathode will comprise a pair of cathodes.

In some embodiments, the cathode bundle is secured together by use of an appropriate material, such as tie wire or tie strap.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be described with reference to the following drawings in which:

FIG. 1 illustrates an end view of a self-dunnaged cathode bundle according to an embodiment of the present invention.

FIG. 2 illustrates transportation of a self-dunnaged cathode bundle according to an embodiment of the present invention.

FIGS. 3A-3D illustrate a number of alternative embodiments for the arrangement of cathodes within the self-dunnaged cathode bundle.

DETAILED DESCRIPTION

In FIG. 1 there is shown a self-dunnaged cathode bundle 10 comprising a first plurality of cathode sheets 11 and a second plurality of cathode sheets 12 stacked on top of each other. Inserted between the first plurality of cathode sheets 11 and the second plurality of cathode sheets 12 there are a pair of deformed cathode sheets 13. Each deformed cathode sheet comprises a pair of supports 14 extending downwardly from an central portion 15 of the deformed cathode. The bend 16 in the cathode sheet is located a sufficient distance from the outer edges 17 of the cathodes to avoid bending the cathode at a point where the thickness of the cathode has tapered. The angle between the supports 14 and the central portion 15 of the deformed cathode is approximately 90°.

Once the cathode bundle 10 is stacked, strapping 18 is applied in order to hold the cathodes in place during transportation. The length of the supports 14 of the pair of deformed cathodes 13 creates a void 19 between cathodes in the cathode bundle 10 of sufficient height to allow the passage of the tines of a forklift or similar device. Thus, the cathode bundle 10 may be simply moved and transported without the need for wooden dunnage.

FIG. 2 illustrates a cathode bundle 10 when being transported. The completed cathode bundle 10 has strapping 18 applied to hold the bundle 10 together when it is being moved. The void 19 created between the first plurality of cathodes 11 and second plurality of cathodes 12 by the deformed cathodes 13 allows a forklift 20 to pick up and move the cathode bundle 10.

FIG. 3A illustrates another embodiment of the invention in which the deformed cathode 13 is placed at the bottom of the self-dunnaged cathode bundle 10. A plurality of cathodes 21 may then be positioned on top of the deformed cathode 13. Alternatively, FIG. 3B shows an arrangement wherein the self-dunnaged cathode bundle 10 is formed by positioning the deformed cathode 13 on top of a plurality of cathodes 21. In yet another embodiment of the invention, illustrated in FIG. 3C, a single cathode 22 is positioned underneath a pair of deformed cathodes 13 and then a plurality of further cathodes 21 is positioned above the pair of deformed cathodes 13 to form the self-dunnaged cathode bundle 10. In yet another embodiment of the invention, illustrated in FIG. 3D, a single cathode 22 is positioned underneath a pair of deformed cathodes 13 and then a plurality of further cathodes 21 is positioned above the pair of deformed cathodes 13 to form the self-dunnaged cathode bundle 10. In this embodiment of the invention the supports 14 of the pair of deformed cathodes 13 extend upwardly from the central portion 15 of the pair of deformed cathodes 13.

Those skilled in the art will appreciate that, in normal practice, self-dunnaged cathode bundles are generally strapped together using any suitable strapping material, such as, for instance, tie wire or tie strap. However, this strapping material has been omitted from FIGS. 3A to 3D for clarity. It will be apparent that some of the self-dunnaged cathode bundles shown in FIGS. 3A to 3D will require the use of lesser amounts of strapping material than others. However, the choice as to which particular self-dunnaged cathode bundle will be desired for use may depend on a number of operational factors.

The self-dunnaged cathode bundle provides a number of significant advantages over existing cathode bundles. By eliminating the use of wooden dunnage, metal refineries may save hundreds of thousands of dollars per year, as well as reducing the amount of waste wood generated by the process. The maintenance requirements needed to replace damaged permanent wooden dunnage are avoided. Occupational health and safety issues caused by wooden dunnage (such as tripping hazards) are also largely overcome. In addition, self-dunnaged cathode bundles eliminate quarantine issued that may arise from using wooden dunnage. Also advantageously, bending the cathodes does not adversely affect the cathode's chemical or physical properties, and the bent cathodes are still suitable for further downstream processing.

Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. It will be understood that the present invention encompasses all such variations and modifications that fall within its spirit and scope. 

1. A method for producing self-dunnaged cathode bundles, comprising forming at least one deformed cathode by bending opposed ends of at least one cathode to form a pair of supports disposed at an angle to a central portion of the at least one deformed cathode, and stacking one or more undeformed cathodes above or below the at least one deformed cathode.
 2. A method for producing self-dunnaged cathode bundles according to claim 1, wherein at least one undeformed cathode is stacked below the at least one deformed cathode, and at least one undeformed cathode is stacked above the at least one deformed cathode.
 3. A method for producing self-dunnaged cathode bundles according to claim 1, wherein the at least one deformed cathode is located at the bottom of the cathode bundle and one or more undeformed cathodes are located above the at least one deformed cathode.
 4. A method for producing self-dunnaged cathode bundles according to claim 1, wherein the at least one deformed cathode is located at the top of the cathode bundle and one or more undeformed cathodes are located below the at least one deformed cathode
 5. A method for producing self-dunnaged cathode bundles according to claim 1 wherein the pair of supports are disposed at an angle of between 85° and 95° to the central portion of the at least one deformed cathode.
 6. A method for producing self-dunnaged cathode bundles according to claim 1 wherein the pair of supports extend substantially downwardly from the central portion of the at least one deformed cathode.
 7. A method for producing self-dunnaged cathode bundles according to claim 1 wherein the pair of supports extend substantially upwardly from the central portion of the at least one deformed cathode.
 8. A method for producing self-dunnaged cathode bundles according to claim 1 wherein the bend to create each of said pair of supports is placed in the at least one deformed cathode at a point between 50 mm and 300 mm from an outer edge of the at least one deformed cathode.
 9. A method for producing self-dunnaged cathode bundles according to claim 1 wherein the at least one deformed cathode is a pair of cathodes.
 10. A method for producing self-dunnaged cathode bundles according to claim 1 wherein the cathode bundles are held together by applying strapping to the cathode bundles.
 11. A self-dunnaged cathode bundle comprising at least one dunnage cathode having a pair of supports disposed at an angle to a central portion, and one or more undeformed cathodes stacked above or below the at least one dunnage cathode.
 12. A self-dunnaged cathode bundle according to claim 11 wherein at least one undeformed cathode is stacked below the at least one dunnage cathode, and at least one undeformed cathode is stacked above the at least one dunnage cathode.
 13. A self-dunnaged cathode bundle according to claim 11 wherein the at least one dunnage cathode is located at the bottom of the cathode bundle and one or more undeformed cathodes are located above the at least one dunnage cathode.
 14. A self-dunnaged cathode bundle according to claim 11 wherein the at least one dunnage cathode is located at the top of the cathode bundle and one or more undeformed cathodes are located below the at least one dunnage cathode
 15. A self-dunnaged cathode bundle according to claim 11 wherein the pair of supports are disposed at an angle of between 85° and 95° to the central portion of the at least one dunnage cathode.
 16. A self-dunnaged cathode bundle according to claim 11 wherein the pair of supports extend substantially downwardly from the central portion of the at least one dunnage cathode.
 17. A self-dunnaged cathode bundle according to claim 11 wherein the pair of supports extend substantially upwardly from the central portion of the at least one dunnage cathode.
 18. A self-dunnaged cathode bundle according to claim 11 wherein the dunnage cathode is formed by bending.
 19. A self-dunnaged cathode bundle according to claim 18 wherein the bend to create each of said pair of supports is placed in the at least one dunnage cathode at a point between 50 mm and 300 mm from and outer edge of the at least one dunnage cathode.
 20. A self-dunnaged cathode bundle according to claim 11 wherein the at least one dunnage cathode comprises a pair of cathodes.
 21. A self-dunnaged cathode bundle according to claim 11 wherein the cathode bundle further comprises one or more straps to hold the cathode bundle together. 